1. Field of the Invention
The present invention relates to windmills or wind turbines having a wind-driven, reciprocating element used to power a reciprocating piston pump, and more particularly to control systems for varying the effective displacement of the pump in accordance with the velocity of available wind.
2. Description of the Prior Art
It has previously been known to vary the effective length of stroke of a windmill driven pump, and thus vary the effective displacement per time unit of the pump, in accordance with wind velocity. This makes it possible to utilize the increasing energy of the wind as wind velocity increases, this energy varying as the cube of the wind velocity. By increasing the length of stroke of the pump as wind velocity increases, more work can be accomplished. In the case of piston pumps, the increased length of stroke provides an increased effective displacement per unit time.
Various proposals have been made for regulating the length of stroke of the pump in proportion to wind velocity. Typical of these proposals is U.S. Pat. No. 1,675,159 to Frederick R. Burch, which utilizes a "regulator setting system" having a fluid power transmitting agent and a speed governor operated by the windmill for regulating the action of the fluid agent in the apparatus in a manner to cause the windmill to operate at a substantially uniform speed under varying velocities of the wind. This sytem is relatively cumbersome, expensive and is not quickly responsive to variations to wind velocity.
Another typical control system is illustrated in U.S. Pat. No. 617,877 to Elmo G. Harris, which also includes a governor system actuated by the rotation of the windmill and utilizing a pressurized fluid valving system to accomplish changes in the length of stroke of the pump.
Another approach to changing the length of stroke of the pump is shown in U.S. Pat. No. 733,799 to Edmond H. Benedict, regulation of the length of stroke of the pump being accomplished by measuring the rate of pump output.
None of the previously known devices control the length of pump stroke in accordance with wind velocity by sensing the velocity of the wind directly, and the Harris and Burch devices require pressurized fluid control systems utilizing a balancing of fluid pressures in the system.